The Aviva Stadium in the Irish capital is scheduled to host three group matches and a last-16 game but there are growing doubts over the issue of fan attendance.
UEFA president Aleksander Ceferin has warned that countries that failed to offer guarantees on supporter numbers could be dropped as hosts.
"The Football Association of Ireland, on advice and guidance from the government, has today notified UEFA that owing to the Covid-19 pandemic it is not in a position at this point to provide assurances on minimum spectator levels at the UEFA Euro 2020 matches due to be held in Dublin in June," the FAI said in a statement.
Ireland has been in a third coronavirus lockdown since late December but will take its first tentative step towards lifting curbs on Monday.
The government has signalled the relaxing of restrictions will be staggered over a period of months after a hasty reopening in late 2020 contributed to a surge in cases.
Dutch on board
Earlier on Wednesday the Dutch Football Association (KNVB) announced it hoped to have "at least 12,000 fans" at the four matches Amsterdam is hosting for the Euro.
The Johan Cruyff Arena will hold the Netherlands' group matches against Ukraine (June 13), Austria (June 17), North Macedonia (June 21) and a round-of-16 match on June 26.
The KNVB said in a statement the scenario it submitted to UEFA is based on the "realistic" assumption that it will be able to fill at least 25 per cent of the 55,000-seat stadium's capacity.
It hopes that "depending on the development of the Covid-19 pandemic, there may be a chance to accommodate more fans".
The KNVB added that spectators wishing to attend matches in Amsterdam will have to comply with the security protocols in place in June and present a negative Covid test result, but warned that the number of fans allowed in could be reduced "if the pandemic worsens in June".
Tournament director in Amsterdam Gijs de Jong said that "there were no guarantees yet," adding that he had received the green light from the Dutch interior ministry and Amsterdam city hall to implement the 12,000-seat scenario.
Spain, Italy opening doors
Spanish media reported on Wednesday that the country's football federation had submitted a document similar to that of the Dutch to UEFA for Spain's three group matches against Sweden (June 14) Poland (June 19) Slovakia (June 23) and a round-of-16 match on June 27 at the San Mames in Bilbao.
That would mean crowds of around 13,000 at the 53,000-capacity stadium in the Basque city.
On Tuesday, the head of Italy's football federation Gabriele Gravina said the Italian government had given the green light for fans to attend Euro matches scheduled for Rome's Stadio Olimpico, including the tournament opener.
The German FA said it has urged health authorities in Munich to make it possible for spectators to be admitted to matches at the Allianz Arena.
Scotland's national clinical director said last week that he was confident Hampden Park in Glasgow would be able to accommodate fans for four Euro 2020 matches in June.
Matches are also scheduled for the Olympic Stadium in Baku, the National Stadium in Bucharest, the Puskas Arena in Budapest, the Parken Stadium in Copenhagen, the Krestovsky Stadium in Saint Petersburg and Wembley Stadium in London, which will host the final.